Axles were made from cold rolled 4130 and tapped on the ends. Corners were knocked off to clear the 3/4" square tube.
Connecting arms:
Idler assembly:
Here's some idler machining at the school:
https://www.youtube.com/watch?v=EDhaW5d9uDk
In the end we didn't use the assemblies in competition but we certainly learned a lot. Maybe in the fall we'll get them sorted... even though the student that designed them has graduated.